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(No Model.)

H. G. SERGEANT.

AIR HEATING APPARATUS.

.No. 546,866. Patented Sept. 24, 1895.

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HENRY G. SERGEANT, OF WESTFIELD, NEW JERSEY, ASSIGNOR TO THE INGERSOLL-SERGEANT DRILL COMPANY, OF NEW YORK, N. Y.

AIR-HEATING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 546,866, dated September 24:, 1895. Application filed January 15, 1895. Serial No. 535,071. (No model.)

To all whom it may concern:

Be it known that I, HENRY O. SERGEANT, of WVestfielrLin the county of Union and State of New Jersey, have invented a new and useful Improvement in Air-Heating Apparatus, of which the following is a specification.

This invention, though applicable to the heating of air for all purposes, is more especially intended for the reheating of compressed air prior to its use in a drilling-engine or other motor.

The object of the improvement is to obtain a heating apparatus for such purpose which is inexpensive in its construction, effective and economical in its operation, and which, by reason of the provision made for unequal expansion of its parts by heat, is very durable.

The invention is illustrated in the accompanying drawings, in which Figure 1 represents a central vertical section of an apparatus embodying my invention. Fig. 2 is a plan view of the same.

Similar letters of reference designate corresponding parts in both figures.

A is a fire-chamber, consisting of a hollow casting in the form of the frustum of a cone erected upon a base B, the lower part of the said chamber constituting a fireplace, wherein the fuel to be employed may be of any suitable kind. As here represented the apparatus is designed for the use of coal, and a fire-grate O is provided on the base 13 at the bottom of the chamber.

D is a jacket surrounding the fire-chamber A concentrically and supported in part on an external flange b provided around the bottom of the said chamber and in part on an internal flange 0 provided at the top of the said chamber. The greater portion of the length of this jacket conforms to the fire-chamber and is only so much larger internally as to leave a very narrow annular space a between the interior of the said jacket and the exterior of the fire-chamber; but the upper and lower portions of the said jacket are swelled circumferentially with a curved profile, as shown at dand e, to form around the top and bottom, respectively, of the fire-chamber an annular channel of much greater width than the space a. The upper channel at has an inlet on one side at f for the ingress of air to be heated, and

the lower channel c has an outlet 9 on the opposite side for the egress of the air which has been heated. The upper and lower parts of the jacket are secured to the flanges b and c by bolts h h, the joints between the chamber A and the jacket being made tight by any suitable packing. At the top of the fire-chamber A is a cover E, which may be removable, and which is represented as provided with a chimney-base t' and an opening j through which to feed the fuel, the said openingj being provided with a suitable door or lid It. The jacket is represented in Fig. 1 as clothed between the swells or channels at e with nonconducting material N. The air to be heated, introduced at f, circulates freely around the channel at, whence it is distributed equally around and through the contracted space a in a thin film in contact with the highly-heated exterior of the fire-chamber A, at the bottom of which it is collected in the channel e to be delivered at the outlet 9. By reason of the conical form of the heating-chamber the air in its downward circulation between said chamber and the jacket is caused to so impinge upon the outer surface of the said chamber as to be most effectively heated.

It will be understood that the fire-chamber A being unavoidably heated to a higher degree than the jacket the expansion of said chamber in a longitudinal or vertical direction will be greater than that of the jacket, and if it were not for some provision to compensate for this unequal expansion it would be impossible to maintain tight joints-at b and c, and the apparatus would in time rack itself to pieces. This compensation is afforded by the swells d and e, which, besides forming channels for the distribution of the air to be heated and thecollection of the heated air, afford just sufficient flexibility at the top and bottom of the jacket to allow it to expand lengthwise in proportion to the expansion of the chamber A by heat and to contract again as the said chamber contracts in cooling.

It is obvious that the compensation for expansion hereinabove explained might be obtained by providing only a single circumferential swell in the jacket; but I prefer to have two such swells, one at the top and the other at the bottom, as in the example which I have selected for illustration. It may be also understood that the inlet for air may be at g to the lower channel 6 and the outlet for air at f from the upper channel cl; but it is preferable, for obvious reasons, that the inlet should be to the upper channel and the outlet from the lower channel, as hereinabove described with reference to the drawings.

WVhat I claim as my invention is 1. In an air heating apparatus, the combination with a conical fire chamber, of an external conical air jacket surrounding said fire chamber and having an inlet in its upper part and an outlet in its lower part, substantially as herein described.

2. In an air heating apparatus, the combination with a fire-chamber, of a surrounding external jacket having a circumferential swell forming between said jacket and fire chamber an annular air channel for ingress or egress of air of greater width than the space between said fire chamber and jacket, substantially as herein set forth.

3. The combination with the conical fire chamber, of the surrounding external conical jacket having in its upper and lower parts respectively circumferential swells forming upper and lower air channels in communication with each other through the intervening narrower space between the said fire chamber and jacket, one of the said channels having an inlet for air to be heated and the other of said channels having an outlet for heated air, substantially as herein set forth.

In testimony whereof I have hereunto signed my name in the presence of two subscribing witnesses.

HENRY C. SERGEAN'P.

'Witnesses:

FREDK. HAYNES, LIDA M. EGBERT. 

